Since August 2003, Dr. Hummel is a staff astronomer with the European Southern Observatory. He spent four years in Santiago, Chile, before moving to Garching, Germany, in May 2007.

Before taking up his appointment at ESO, Dr. Hummel was an astronomer with the United States Naval Observatory. He joined the Optical Interferometer Project in 1991 as a research associate and conducted extensive observations using the Mark III Stellar Interferometer on Mt. Wilson (CA) and the Navy Prototype Optical Interferometer at Lowell Observatory on Anderson Mesa (AZ).

His primary research interests include the determination of physical parameters of stars in multiple stellar systems through interferometric and spectrocopic observations. He also works on near- and mid-infrared observations of pre-main sequence stars. He has written comprehensive data reduction and modeling software for Mark III and NPOI data, capable of combining interferometric and spectroscopic data to analyze hierarchical stellar systems. Dr. Hummel was also involved in the reduction of wide angle astrometric data from the NPOI.

Dr. Hummel obtained his PhD from the University of Bonn, while working at the Max-Planck-Institut for Radioastronomy. Dr. Hummel has considerable experience in long baseline interferometry, beginning with VLBI in the radio, which he used to study jets of quasars, and continuing with the MERLIN and VLA interferometers for further studies of extragalactic radio sources. He has used his knowledge of imaging radio interferometric data which he acquired during his work in Bonn to extract some of the first images of spectroscopic binaries from optical interferometric data, and has developed an imaging algorithm for multi-wavelength aperture synthesis observations.